Appendix A Technical specifications 97Nortel VPN Router Installation — VPN Router 1750Single V.35/X.21 WAN interface cardThe single V.35/X.21 WAN interface card has a single DB28S connector thatprovides the signals needed to interface to V.35 and X.21 equipment. Figure 43shows the single V.35/X.21 WAN interface card.Figure 43 Single V.35/X.21 WAN interface cardYou need a DSU/CSU (digital service unit/channel service unit) between theWAN connection and the gateway. You can order a V.35 or X.21 cable to attach tothe connector. With this cable, the WAN adapter can function as DTE (dataterminal equipment).Table 32 provides the V.35 cable pinouts. Table 33 on page 99 provides the X.21cable pinouts. (The pair suffix A or B refers to an individual wire within a twistedpair.)3 Ring4 N/CTable 32 V.35 cable pinoutsStandard-wiredend 28-pin male Signal namePair numberand conductorSpecial-wiredend 34-pin male Notes2 TXDA pair 1A P14 TXDB pair 1B S3 RXDA pair 2A R16 RXDB pair 2B T15 TXCA pair 3A Y12 TXCB pair 3B AATable 31 MV.90 modem cable pinouts (continued)Pin FunctionCS160011A
